Acute Asthma Exacerbation (Adults) 🫁
Adult acute asthma attack assessment and management based on BTS/SIGN SIGN 158 QRG and Irish NCEC National Clinical Guideline No. 14: severity (PEF), oxygen, bronchodilators, steroids, magnesium, admission and discharge.
📖 Overview
- Scope: acute asthma attack in adults (and adolescents aged 16+). Children under 16 are out of scope here.
- Primary reference: BTS/SIGN Asthma Guideline Quick Reference Guide (SIGN 158, Jul 2019), acute asthma in adults (PDF pp. 17–18). Irish practice: NCEC National Clinical Guideline No. 14 (2015), developed with the HSE National Clinical Programme for Asthma (update underway).
- NCEC No. 14 was largely adapted from earlier BTS/SIGN / GINA guidance, so thresholds align closely. Where local hospital protocols refine ICU or IV pathways, follow them.
- Classify severity early using PEF (% best, or % predicted if recent best unknown) plus clinical features. Treat immediately; do not delay therapy for investigations.
🔍 Immediate Assessment
- ABCDE. Look for life-threatening features first: silent chest, cyanosis, poor respiratory effort, arrhythmia, hypotension, exhaustion, altered consciousness, collapse.
- Measure SpO₂, respiratory rate, heart rate, ability to speak in sentences/phrases/words, accessory muscle use, and auscultation. None of these alone is specific; their absence does not exclude a severe attack (BTS/SIGN).
- Record PEF (or FEV₁ if available) as % of previous best (most useful); use % predicted only if best is unknown. Use the same type of peak-flow meter where possible.
- History: usual controllers/relievers, recent oral steroids, previous ICU/near-fatal asthma, hospital/ED attendances, triggers (infection, allergen, NSAID, beta-blocker), smoking, pregnancy, adverse psychosocial factors (severe asthma + psychosocial risk factors → higher risk of death).
- Do not delay oxygen or bronchodilators while waiting for PEF if the patient is too breathless to perform it.
📊 Severity Classification (BTS/SIGN)
- Grade by the single worst feature present. Any one criterion is enough (e.g. RR ≥25 alone = acute severe even if PEF is higher).
- Life-threatening features apply in a patient with severe asthma: any one feature is enough (BTS/SIGN). HSE NCP also lists bradycardia as a life-threatening sign.
Mild (HSE NCP)
- PEF (% best or predicted)
- >75%
- Clinical features (any one)
- Talks in sentences; can lie down; mild–moderate wheeze (used for Irish discharge follow-up timing)
Moderate acute
- PEF (% best or predicted)
- >50–75%
- Clinical features (any one)
- Increasing symptoms; no features of acute severe asthma
Acute severe
- PEF (% best or predicted)
- 33–50%
- Clinical features (any one)
- RR ≥25/min; HR ≥110/min; inability to complete sentences in one breath
Life-threatening
- PEF (% best or predicted)
- <33%
- Clinical features (any one)
- SpO₂ <92%; PaO₂ <8 kPa; “normal” PaCO₂ (4.6–6.0 kPa); altered conscious level; exhaustion; arrhythmia; hypotension; cyanosis; silent chest; poor respiratory effort; bradycardia (HSE)
Near-fatal
- PEF (% best or predicted)
- N/A
- Clinical features (any one)
- Raised PaCO₂ and/or requiring mechanical ventilation with raised inflation pressures
| Severity | PEF (% best or predicted) | Clinical features (any one) |
|---|---|---|
| Mild (HSE NCP) | >75% | Talks in sentences; can lie down; mild–moderate wheeze (used for Irish discharge follow-up timing) |
| Moderate acute | >50–75% | Increasing symptoms; no features of acute severe asthma |
| Acute severe | 33–50% | RR ≥25/min; HR ≥110/min; inability to complete sentences in one breath |
| Life-threatening | <33% | SpO₂ <92%; PaO₂ <8 kPa; “normal” PaCO₂ (4.6–6.0 kPa); altered conscious level; exhaustion; arrhythmia; hypotension; cyanosis; silent chest; poor respiratory effort; bradycardia (HSE) |
| Near-fatal | N/A | Raised PaCO₂ and/or requiring mechanical ventilation with raised inflation pressures |
💊 Immediate Management (all acute attacks)
- Oxygen: give controlled supplementary oxygen to hypoxaemic patients; aim SpO₂ 94–98% (BTS/SIGN). Do not delay oxygen if oximetry is not yet available; start SpO₂ monitoring as soon as possible.
- β₂ agonist early and in high dose: mild/moderate — pMDI + spacer, titrate to response (HSE pathway: up to 12 puffs); or salbutamol 5 mg via oxygen-driven nebuliser.
- In hospital, ambulance, and primary care, nebulisers for β₂ agonists should preferably be oxygen-driven. If acute severe or life-threatening features are present, use an oxygen-driven nebuliser.
- Give steroids in adequate doses to all patients with an acute asthma attack: prednisolone 40–50 mg orally, or IV hydrocortisone 100 mg if oral not possible (methylprednisolone 125 mg IV is listed in the HSE NCP ED pathway).
- Continue oral prednisolone 40–50 mg daily until recovery (minimum 5 days).
- Repeat salbutamol via spacer or neb at 15–30 minute intervals according to response. If poorly responsive to an initial bolus, consider continuous nebulisation (HSE pathway: salbutamol 5–10 mg/hour with an appropriate nebuliser).
- Pregnancy: treat acute asthma as for non-pregnant patients (including systemic steroids and magnesium if indicated); maintain SpO₂ 94–98%. Acute severe asthma in pregnancy is an emergency — continuous fetal monitoring and early liaison with obstetrics / critical care (BTS/SIGN).
🚨 Acute Severe / Life-Threatening Add-Ons
- Call for senior / ICU / specialist help immediately if any life-threatening features are present. Keep the patient accompanied by a nurse or doctor (HSE NCP).
- Add nebulised ipratropium bromide 0.5 mg (4–6 hourly) to β₂ agonist treatment for acute severe or life-threatening asthma, or poor initial response to β₂ agonist (BTS/SIGN / NCEC).
- ABG if SpO₂ <92% or other life-threatening features. Markers of severity: “normal” or raised PaCO₂, PaO₂ <8 kPa, low pH (or high H⁺).
- 12-lead ECG if life-threatening features, arrhythmia, or cardiovascular compromise (HSE NCP ED pathway).
- Consider a single dose of IV magnesium sulphate 1.2–2 g over 20 minutes for acute severe asthma (PEF <50% best or predicted) with poor initial response to inhaled bronchodilators. Use only after discussion with senior medical staff (BTS/SIGN). Irish ED pathways often use 2 g.
- Nebulised magnesium sulphate is not recommended in adults (BTS/SIGN).
- Correct fluids and electrolytes, especially hypokalaemia (HSE NCP; β₂ agonists and steroids can lower K⁺).
- Reserve IV β₂ agonists for patients in whom inhaled therapy cannot be used reliably.
- Do not sedate acute asthma patients unless required for anaesthetic or intensive care procedures.
- Routine antibiotics are not indicated unless there is clear evidence of bacterial infection.
🔬 Investigations & Monitoring
- Repeat PEF after bronchodilator and at intervals thereafter; chart response.
- Continuous pulse oximetry while acute; aim SpO₂ 94–98%. SpO₂ guides need for ABG.
- Bloods: FBC, U&E (watch K⁺), consider CRP if infection suspected.
- CXR is not routinely recommended unless: suspected pneumomediastinum or pneumothorax; suspected consolidation; life-threatening asthma; failure to respond satisfactorily; or requirement for ventilation (BTS/SIGN).
- Monitor for exhaustion, rising PaCO₂, falling SpO₂, and deteriorating PEF: these trigger ICU referral.
🏥 Admission & Discharge
- Admit any feature of a life-threatening or near-fatal asthma attack (BTS/SIGN / NCEC).
- Admit any feature of a severe asthma attack persisting after initial treatment (BTS/SIGN / NCEC).
- Irish NCEC: also admit if PEF is <75% best or predicted after initial treatment.
- Patients whose PEF is >75% best or predicted one hour after initial treatment may be discharged from ED unless other reasons favour admission (BTS/SIGN), e.g. still significant symptoms; concerns about adherence; living alone / socially isolated; psychological problems; physical disability or learning difficulties; previous near-fatal asthma; attack despite adequate oral steroids pre-presentation; presentation at night; pregnancy (NCEC / HSE NCP list).
- GPs: refer to hospital anyone with features of acute severe or life-threatening asthma (NCEC / HSE).
- Refer to ICU any patient needing ventilatory support, or acute severe/life-threatening asthma failing therapy (deteriorating PEF, persisting/worsening hypoxia, hypercapnia, falling pH / rising H⁺, exhaustion/feeble respiration, drowsiness/confusion, respiratory arrest). Accompany ICU transfers with a doctor able to intubate.
- If life-threatening features were present, Irish pathways advise admit for a minimum of 24 hours with close observation.
🏠 Discharge & Follow-Up
- If nebulised β₂ agonist was given before arrival, consider an extended observation period before discharge. Consider delaying discharge until 08:00 if after midnight (HSE NCP).
- Continue prednisolone 40–50 mg daily until recovery (minimum 5 days). Ensure supply of inhaled corticosteroid and reliever; check inhaler technique. Provide PEF meter advice and a written personalised asthma action plan where possible (BTS/SIGN / HSE NCP).
- Inform the patient’s GP / primary care practice within 24 hours of discharge from ED or hospital (BTS/SIGN). Fax or email the discharge letter where possible (HSE NCP).
- GP clinical review within 2 working days of presentation for moderate / severe / life-threatening attacks; within 2 weeks if mild (HSE NCP discharge bundle).
- After admission with a severe attack, arrange respiratory specialist follow-up for at least one year. Keep near-fatal asthma under specialist supervision indefinitely (BTS/SIGN). HSE NCP also advises asthma/respiratory service follow-up within 4 weeks after ED/hospital presentation.
- Consider psychosocial factors before discharge; low threshold to admit if unsafe to go home.
Note Template
Ready-to-use clinical note structure
🕒 04 / 11 / 2026 — 21:42 ATRP re: acute asthma exacerbation Patient: [age] [sex] Admission Dx: [reason for admission] PMHx: asthma [mild / moderate / severe]; previous near-fatal / ICU [Y/N]; recent ED/hospital [Y/N] 🧾 Hx: • Onset / trigger: [infection / allergen / NSAID / other / unknown] • Usual inhalers: [ICS / ICS-LABA / SABA]; oral steroids recently [Y/N] • Ability to speak: [sentences / phrases / words] • Smoking / adherence concerns: [ ] 🩺 Exam: • RR: __ SpO₂: __% on __ HR: __ BP: __ GCS / alertness: __ • PEF: __ L/min (__% best / predicted); best known: __ • Life-threatening features: [none / SpO₂<92% / silent chest / list] • Chest: [wheeze / silent chest / accessory muscles / cyanosis] 🔬 Investigations: • ABG: [if done — PaO₂ / PaCO₂ / pH] • K⁺: __ CXR: [not indicated / findings] 📋 Impression: Acute asthma — [mild / moderate / acute severe / life-threatening / near-fatal] (NCEC No. 14) 📌 Plan: • O₂ to SpO₂ 94–98% • Salbutamol [spacer puffs / neb 5 mg O₂-driven]; repeat __ • Ipratropium 0.5 mg neb [Y/N] • Prednisolone 40–50 mg PO; course __ days (minimum 5) • MgSO₄ IV [given / considered / N/A — senior discussion if used] • Admit / discharge: [observe / admit / HDU-ICU]; senior informed [Y/N] • Discharge checklist if applicable: ICS + SABA supply, inhaler technique, action plan, GP informed ≤24 h (BTS/SIGN), GP review [≤2 working days if ≥moderate / ≤2 weeks if mild — HSE NCP], respiratory follow-up within 4 weeks (HSE NCP) 👤 [Your Name], [Role] IMC: _______
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